擅长:python、mysql、java
<p>使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.wide_to_long.html" rel="nofollow noreferrer">^{<cd1>}</a>:</p>
<pre><code>new_df =(pd.wide_to_long(df.reset_index(),['item_id','item_name'],
j='n',i='index',sep = '_')
.reset_index(drop=True)
.rename(columns = {'item_id':'items_id','item_name':'item_names'}) )
print(new_df)
</code></pre>
<p><strong>输出</strong></p>
<pre><code> items_ids item_names
0 1.0 it1
1 2.0 it2
2 3.0 NaN
3 NaN it3
</code></pre>
<hr/>
<p><strong>初始测向:</strong></p>
<pre><code>print(df)
item_id_1 item_name_1 item_id_2 item_name_2 item_id_3 item_name_4
0 1 it1 2 it2 3 it3
</code></pre>